angiogenesis factor a substance that causes the growth of new blood vessels, found in tissues with high metabolic requirements such as cancers and the retina. It is also released by hypoxic macrophages at the edges or outer surface of a wound and initiates revascularization in wound healing.

2. a preparation of factor VIII administered intravenously for the prevention or treatment of hemorrhage in patients with hemophilia A and the treatment of von Willebrand disease, hypofibrinogenemia, and coagulation factor XIII deficiency. Included are preparations derived from human plasma (antihemophilic factor, cryoprecipitated antihemophilic factor) or porcine plasma (antihemophilic factor [porcine]) and those produced by recombinant technology antihemophilic factor [recombinant]).

atrial natriuretic factor (ANF) a hormone produced in the cardiac atrium; an inhibitor of renin secretion and thus of the production of angiotensin, and a stimulator of aldosterone release. Its effect is increased excretion of water and sodium and a lowering of blood pressure.

factor B a complement component that participates in the alternative complement pathway.

C3 nephritic factor (C3 NeF) an autoantibody that stabilizes the alternative complement pathway C3 convertase, preventing its inactivation by factor h, resulting in complete consumption of plasma C3; it is found in the serum of many patients with type II membranoproliferative glomerulonephritis.

hematopoietic growth f's a group of substances with the ability to support hematopoietic colony formation in vitro, including erythropoietin, interleukin-3, and colony-stimulating factors. All except erythropoietin stimulate mature cells, have overlapping capabilities to affect progenitor cells of several blood cell lines, and also affect cells outside the hematopoietic system.

histamine-releasing factor (HRF) a lymphokine, believed to be produced by macrophages and B lymphocytes, that induces the release of histamine by IgE-bound basophils. It occurs in late phase allergic reaction, six or more hours after contact with the antigen, in sensitive individuals.

homologous restriction factor (HRF) a regulatory protein that binds to the membrane attack complex in autologous cells, inhibiting the final stages of complement activation.

factor I a plasma enzyme that regulates both classical and alternative pathways of complement activation by inactivating their C3 convertases.

immunoglobulin-binding factor (IBF) a lymphokine having the ability to bind IgG complexed with antigen and prevent complement activation.

insulinlike growth f's (IGF) insulinlike substances in serum that do not react with insulin antibodies; they are growth hormone–dependent and possess all the growth-promoting properties of the somatomedins.

intensification factor in radiology, the comparative increase in light transmission when films are exposed in the presence of intensifying screens compared to that in the absence of screens.

intrinsic factor a glycoprotein secreted by the parietal cells of the gastric glands, necessary for the absorption of cyanocobalamin (vitamin B12). Its absence results in pernicious anemia.

LE factor an immunoglobulin that reacts with leukocyte nuclei, found in the serum in systemic lupus erythematosus.

lymphocyte mitogenic factor (LMF) (lymphocyte-transforming factor) a substance that is released by lymphocytes stimulated by specific antigen and causes nonstimulated lymphocytes to undergo blast transformation and cell division; called also blastogenic factor.

minification factor in radiology, the gain in light achieved by a reduction in size of the output phosphor from the input phosphor size.

osteoclast-activating factor (OAF) a lymphokine that stimulates bone resorption; it may be involved in the bone resorption associated with multiple myeloma and other hematologic neoplasms or inflammatory disorders such as rheumatoid arthritis and periodontal disease.

platelet-activating factor (PAF) a substance released by basophils and mast cells in immediate hypersensitivity reactions, and by macrophages and neutrophils in other inflammatory reactions; it leads to bronchoconstriction, platelet aggregation, and release of vasoactive substances from platelets.

releasing f's factors elaborated in one structure (as in the hypothalamus) that effect the release of hormones from another structure (as from the anterior pituitary gland), including corticotropin-releasing factor, melanocyte-stimulating hormone–releasing factor, and prolactin-releasing factor. Applied to substances of unknown chemical structure, while substances of established chemical identity are called releasing hormones.

Rh factor a type of agglutinogen found on some erythrocytes; see also rh factor.

rheumatoid factor (RF) antibodies directed against antigenic determinants on IgG molecules, found in the serum of about 80 per cent of patients with classic or definite rheumatoid arthritis; but in only about 20 per cent of patients with juvenile rheumatoid arthritis; rheumatoid factors may be IgM, IgG, or IgA antibodies, although serologic tests measure only IgM. Rheumatoid factors also occur in other connective tissue diseases and infectious diseases.

risk factor an agent or situation that is known to make an individual or population more susceptible to the development of a specific negative condition.

risk factor (omaha) an environmental, psychosocial, or physiologic event or health related behavior that increases the client's exposure or vulnerability to the development of a client problem; the nurse's knowledge base of risk factors is used to identify potential problem modifiers in the Problem Classification scheme of the omaha system.

transfer factor (TF) a factor occurring in sensitized lymphocytes that can transfer delayed hypersensitivity to a formerly nonreactive individual; see also transfer factor.

tumor necrosis factor (TNF) either of two lymphokines produced primarily by cells of the immune system, capable of causing in vivo hemorrhagic necrosis of certain tumor cells but not normal cells. They also destroy cells associated with the inflammatory response. They have been used as experimental anticancer agents but can also induce shock when bacterial endotoxins cause their release. Tumor necrosis factor α, formerly called cachectin, contains 157 amino acids and is produced by macrophages, eosinophils, and NK cells. Tumor necrosis factor β is lymphotoxin and contains 171 amino acids.

vascular endothelial growth factor (VEGF) (vascular permeability factor (VPF)) a peptide factor that stimulates the proliferation of cells of the endothelium of blood vessels; it promotes tissue vascularization and is important in blood vessel formation in tumors.

von Willebrand's factor (vWF) a glycoprotein synthesized in endothelial cells and megakaryocytes that circulates complexed to coagulation factor VIII. It is involved in adhesion of platelets to damaged epithelial surfaces and may participate in platelet aggregation. Deficiency results in the prolonged bleeding time seen in von Willebrand's disease.

fac·tor

(fak'tŏr),

1. One of the contributing causes in any action.

2. One of the components that by multiplication makes up a number or expression.

factor

angiogenesis factor a substance that causes the growth of new blood vessels, found in tissues with high metabolic requirements and also released by macrophages to initiate revascularization in wound healing.

C3 nephritic factor (C3 NeF) an autoantibody that stabilizes the alternative complement pathway C3 convertase, preventing its inactivation by factor H and resulting in complete consumption of plasma C3; it is found in the serum of many patients with type II membranoproliferative glomerulonephritis.

coagulation factors substances in the blood that are essential to the clotting process and hence, to the maintenance of normal hemostasis. They are designated by Roman numerals, to which the notation “a” is added to indicate the activated state. See also platelet f's .

factor Ifibrinogen: a high-molecular-weight plasma protein converted to fibrin by the action of thrombin. Deficiency results in afibrinogenemia or hypofibrinogenemia.

factor IIprothrombin: a plasma protein converted to thrombin by activated factor X in the common pathway of coagulation. Deficiency leads to hypoprothrombinemia.

factor XStuart factor: a storage-stable factor that participates in both the intrinsic and extrinsic pathways of blood coagulation, uniting them to begin the common pathway of coagulation; as part of the prothrombinase complex, activated factor X activates prothrombin. Deficiency may cause a systemic coagulation disorder. The activated form is called also thrombokinase.

colony-stimulating factors a group of glycoprotein lymphokines, produced by blood monocytes, tissue macrophages, and stimulated lymphocytes and required for the differentiation of stem cells into granulocyte and monocyte cell colonies; they stimulate the production of granulocytes and macrophages and have been used experimentally as cancer agents.

factor D a serine protease of the alternative complement pathway that cleaves factor B bound to C3b, releasing Ba while leaving Bb bound to C3b to form the C3 convertase C3bBb.

decay accelerating factor (DAF) a protein of most blood cells as well as endothelial and epithelial cells, CD55; it protects the cell membranes from attack by autologous complement.

glucose tolerance factor a biologically active complex of chromium and nicotinic acid that facilitates the reaction of insulin with receptor sites on tissues.

granulocyte colony-stimulating factor (G-CSF) a colony-stimulating factor that stimulates the production of neutrophils from precursor cells.

granulocyte-macrophage colony-stimulating factor (GM-CSF) a colony-stimulating factor that binds to stem cells and most myelocytes and stimulates their differentiation into granulocytes and macrophages.

growth factor any substance that promotes skeletal or somatic growth, usually a mineral, hormone, or vitamin.

factor H a glycoprotein that acts as an inhibitor of the alternative pathway of complement activation.

histamine-releasing factor (HRF) a lymphokine that induces the release of histamine by IgE-bound basophils in late phase allergic reaction.

homologous restriction factor (HRF) a regulatory protein that binds to the membrane attack complex in autologous cells, inhibiting the final stages of complement activation.

factor I a plasma enzyme that regulates both classical and alternative pathways of complement activation by inactivating their C3 convertases.

inhibiting factors factors elaborated by one body structure that inhibit release of hormones by another structure; applied to substances of unknown chemical structure, while those of established chemical identity are called inhibiting hormones.

insulinlike growth factors (IGF) insulin-like substances in serum that do not react with insulin antibodies; they are growth hormone–dependent and possess all the growth-promoting properties of the somatomedins.

intrinsic factor a glycoprotein secreted by the parietal cells of the gastric glands, necessary for the absorption of vitamin B12. Lack of intrinsic factor, with consequent deficiency of vitamin B12, results in pernicious anemia.

LE factor an antinuclear antibody having a sedimentation rate of 7S and reacting with leukocyte nuclei, found in the serum in systemic lupus erythematosus.

releasing factors factors elaborated in one body structure that cause release of hormones from another structure; applied to substances of unknown chemical structure, while those of established chemical identity are called releasing hormones.

resistance transfer factor (RTF) the portion of an R plasmid containing the genes for conjugation and replication.

Rh factor , Rhesus factor genetically determined antigens present on the surface of erythrocytes; incompatibility for these antigens between mother and offspring is responsible for erythroblastosis fetalis.

rheumatoid factor (RF) a protein (IgM) detectable by serological tests, which is found in the serum of most patients with rheumatoid arthritis and in other related and unrelated diseases and sometimes in apparently normal persons.

risk factor a clearly defined occurrence or characteristic that has been associated with the increased rate of a subsequently occurring disease.

transforming growth factor (TGF) any of several proteins secreted by transformed cells and causing growth of normal cells, although not causing transformation.

tumor necrosis factor either of two lymphokines that cause hemorrhagic necrosis of certain tumor cells but do not affect normal cells; they have been used as experimental anticancer agents. Tumor necrosis factor α (formerly cachectin ) is produced by macrophages, eosinophils, and NK cells. Tumor necrosis factor β, is lymphotoxin.

fac·tor

5. An event, characteristic, or other definable entity that brings about a change in a health condition.

6. A categoric independent variable used to identify, by means of numeric codes, membership in a qualitatively identifiable group (e.g., "overcrowding is a factor in disease transmission.").

[L. maker, causer, fr. facio, to make]

factor

1. Any kind of biological material that causes a particular effect.

2. An effector whose function is known but which has not yet been chemically identified.

3. One of the components in the blood coagulation cascade.

Factor

Any of several substances necessary to produce a result or activity in the body. The term is used when the chemical nature of the substance is unknown. In endocrinology, when the chemical nature is known, factors are renamed hormones.

n a factor apparently necessary for the formation of a prothrombin-converting substance in blood and tissue extracts–i.e., intrinsic and extrinsic prothrombin activators. A deficiency results in parahemophilia (hypoproaccelerinemia).

factor VI,

n term formerly used to indicate an intermediate product in the formation of thromboplastin and also used synonymously with accelerin and activated factor V. It has no designation at present.

n a deficiency associated with a lack of vitamin K. A deficiency may be congenital, or it may be acquired in liver disease, or from prothrombinopenic agents used in anticoagulation therapy; it results in a prolonged (quantitative) one-stage prothrombin time test.

n a factor essential for the formation of blood thromboplastin. A deficiency results in classic hemophilia (hemophilia A); the clotting time is prolonged, and thromboplastin and prothrombin conversion is diminished.

n a factor that is active in the formation of intrinsic blood thromboplastin. A deficiency results in Christmas disease (hemophilia B), which is caused by a decrease in the amount of thromboplastin formed.

factor X (Stuart-Prower factor, Stuart factor, Prower factor),

n a factor influencing the yield of intrinsic (plasma) thromboplastin. A deficiency results in a prolonged one-stage prothrombin time. Brain tissue or Russell's viper venom are used to test for thromboplastin deficiency.

n a factor the absence of which results in a long clotting time and abnormal prothrombin consumption and thromboplastin generation tests when tests are carried out in glass tubes. No abnormal bleeding tendency occurs with a deficiency of the factor.

factor XIII,

n a coagulation factor present in normal plasma that acts with calcium to produce an insoluble fibrin clot. Also called fibrinase or fibrin stabilizing factor.

n a coagulation accelerator product formed by the interaction of active factor XII and factor XI.

factor, Castle's intrinsic (intrinsic factor),

n.pr a factor produced by the gastric mucosa and possibly the duodenal mucosa, and considered to be responsible for the absorption of vitamin B12. See also anemia, pernicious.

factor, Christmas,

n See factor IX.

factor, clot-promoting,

n See factor XII.

factor, clotting,

n the “trace” proteins (excluding calcium) present in normal blood in such small amounts (except fibrinogen) that their presence is usually established by deductive reasoning and by genetic and biochemical characteristics. They are associated with thromboplastic activity and the conversion of prothrombin to thrombin.

n the limited factors that include dental plaque, bacterial toxins and irritants, calculus, food impaction, and other surface and locally placed irritants that are capable of injuring the periodontium.

n the substances with thromboplastic activity contributed by the plasma. Included are the antihemophilic factor, Christmas factor, plasma thromboplastin antecedent, and Hageman factor. See also factor VIII.

factor, plasma thromboplastin, A (PTF-A),

n See factor VIII.

factor, plasma thromboplastin, B (PTF-B),

n See factor IX.

factor, plasma thromboplastin, C (PTF-C),

n See factor XI.

factor, plasma thromboplastin, D (PTF-D),

n this factor is considered by some to be a fourth plasma substance with thromboplastic activity; not well characterized.

factor, plasma, X,

n See factor IX.

factor, platelet,

n a substance on or in the surface of blood platelet necessary for coagulation in the absence of extravascular thromboplastic substances.

factor, platelet, 1,

n either factor V or a factor with factor V activity; absorbed on platelets and accelerates conversion of prothrombin to thrombin.

factor, platelet, 2,

n a substance that accelerates the conversion of fibrinogen to fibrin.

factor, platelet, 3,

n a substance associated with thromboplastin generation activity.

factor, platelet, 4,

n an antiheparin factor.

factor, prothrombin conversion,

n See factor VII.

factor, prothrombin-converting,

n See factor VII.

factor, Prower,

n.pr See factor X.

factor, psychosomatic,

n the psychic, mental, or emotional factors that play a role in determining the initiation, course, and extent of a physical process, either directly or indirectly. Psychosomatic factors have been implicated in bruxism, clenching, and other oral habits.

factor, PTA (plasma thromboplastin antecedent factor),

n See factor XI.

factor, reparative,

n the ability of the tissues to heal or regenerate when they have been subjected to injury or disease.

factor, Rh,

n the agglutinogens of red blood cells responsible for isoimmune reactions such as occur in erythroblastosis fetalis and incompatible blood transfusions.

factor, spreading,

n an enzyme that increases the permeability of ground substance.

factor, stable,

n See factor VII.

factor, Stuart,

n.pr See factor X.

factor, Stuart-Prower,

n.pr See factor X.

factor, third thromboplastic,

n See factor C.

factor

an agent or element that contributes to the production of a result. In epidemiology and statistics called also a variable because the factor may have a number of values. In an experiment a factor is a type of treatment and in the experiment the factor will be represented in different groups by different values. Such a factor may originate spontaneously or be introduced by an investigator.

factor analysis

a statistical method for analyzing the correlations between several variables.

antihemorrhagic factor

vitamin K.

antinuclear factor (ANF)

antinuclear antibody.

antirachitic factor

vitamin D.

factor B

a complement component (C3 proactivator) that participates in the alternate complement pathway.

C3 nephritic factor

a gamma globulin that is not an immunoglobulin, which is found in the plasma of certain individuals with membranoproliferative glomerulonephritis associated with hypocomplementemia; it initiates the alternate complement pathway.

citrovorum factor

folinic acid.

clotting f's, coagulation f's

factors essential to normal blood clotting, whose absence, diminution or excess may lead to abnormality of the clotting mechanism. See also clotting factors.

factor D

a factor that, when activated, serves as a serine esterase in the alternate complement pathway.

extrinsic factor

a hematopoietic vitamin that combines with intrinsic factor for absorption from the intestine and is needed for erythrocyte maturation; called also cyanocobalamin and vitamin B12.

F factor, fertility factor

the plasmid that determines the mating type of conjugating bacteria, being present in the donor (male) bacterium and absent in the recipient (female).

a glycoprotein secreted by the parietal cells of the gastric glands, necessary for the absorption of vitamin B12 (cyanocobalamin, extrinsic factor). Its absence in humans results in pernicious anemia. Porcine stomach is a very rich source.

LE factor

an immunoglobulin (a 7S antibody) that reacts with leukocyte nuclei, found in the serum in systemic lupus erythematosus.

factor loading

a relationship between observable manifestations (or variables) and the underlying factors affecting the variables.

lymph node permeability factor (LNPF)

a substance from normal lymph nodes which produces vascular permeability.

lymphocyte transforming factor (LTF)

a lymphokine causing transformation and clonal expansion of lymphocytes.

osteoclast activating factor

substance produced by lymphocytes which facilitates bone resorption.

platelet f's

factors important in hemostasis that are contained in or attached to the platelets. See also platelet factors.

platelet-activating factor (PAF)

an immunologically produced substance which leads to clumping and degranulation of blood platelets.

R factor, resistance factor

a bacterial plasmid (R plasmid) which carries genes for antimicrobial resistance; it can be transmitted to other bacterial cells by conjugation, as well as to daughter cells.

release factor

a protein that binds directly to any stop codon that reaches the A site on the ribosome.

releasing f's

factors elaborated in one structure (as in the hypothalamus) that effect the release of hormones from another structure (as from the anterior pituitary gland), including corticotropin releasing factor, melanocyte-stimulating hormone releasing factor and prolactin releasing factor. Applied to substances of unknown chemical structure, while substances of established chemical identity are called releasing hormones.

transfer factor (TF)

a factor released from sensitized lymphocytes that has the capacity to transfer delayed hypersensitivity to a normal (nonsensitized) animal. See also transfer factor.

Patient discussion about factor

Q. What Are the Risk Factors for Developing Stroke? My father had a stroke recently, at the age of 73. What are the risk factors for developing this?

Q. Regarding risk-factor assessment? Hello, I am……….., I heard ACSM has recently issued a new edition of its exercise guidelines. Were any changes made regarding risk-factor assessment?

A. Are you fitness professional? I understand that you are very much interested in food guidelines. It can be difficult to keep up with the latest guidelines and standards. This is particularly true this year, which has seen new USDA Food Guidelines in January, a revised Food Pyramid in May and, most recently, the release of the 7th edition of ACSM’s Guidelines for Exercise Testing and Prescription. The good news is that the ACSM risk factors have been minimally revised. For your reference, here is a summary of what has and has not changed for the 2006 edition.

Q. Is obesity a risk factor for Dementia?

A. The answer is YES. In fact, many of the risk factors for heart disease, such as high blood pressure, blood glucose levels, insulin resistance, and overweight, are also risk factors for dementia, in addition to genetic predisposition for the disease.

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